Continuous micro anode guided electroplating device and method thereof

ABSTRACT

A continuous micro anode guided electroplating device and a method thereof are revealed. By real-time image monitoring and capillary action of the micro/nanoscale tube, a three-dimensional microstructure is deposited on a workpiece at the cathode. The deposit is growing smoothly under the real-time image monitoring. Moreover, the workpiece is not immersed in an electrolyte so that contaminations of the workpiece caused by electrolyte are reduced.

The current application is a divisional application of, and claims apriority to U.S. Ser. No. 12/570,080 filed on Sep. 30, 2009, whichclaims a foreign priority to application of Taiwan 098117693 filed onMay 27, 2009.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a micro anode guided electroplatingdevice and a method thereof, especially to a continuous micro anodeguided electroplating device and a method thereof.

2. Description of Related Art

Along with fast development of and great advancement in moderntechnology, the electronic products are getting compact and lightweighted. Similarly, the establishment of micromechanical devicesprovides more benefits. When the mechanical devices are getting smaller,its resonance frequency increases. Thus high bandwidth accelerometersand pressure gauges are produced. The microelements integrate drivers,limbs, sensors, processors and power supplies so as to move around theworld under the microscope and applied to medical field.

Milling, welding and fastening of conventional mechanical deviceshaven't achieved the space resolution required by the microelements.Integrated circuits have been widely applied to mechanical devices,electromechanical devices and opto-electro-mechanical systems inmillimeter size and micrometer size. But the uniform thickness structurewith low aspect ratio is unable to achieve optimal performance. Althoughthe aspect ratio can be increased by the lithographic technology such asLIGA (Lithography Electroforming Micro Molding), the lithographictechnology is a two-dimensional manufacturing method. Thethree-dimensional structure is produced by laser cutting, Laser AssistedChemical Vapor Deposition, and stereolithography. The most common wayused is lithographic technology in which thin films are selectivelyremoved by etching to leave the desired film pattern after deposition.By local heating or setting a small piece of electrode near thesubstrate for local reaction, local deposition rate is improved.

Moreover, mechanical devices can also be produced by local microelectroplating. In the local micro electroplating, a three-dimensionalmicro positioning member drives a micro anode so that the micro anodemoves in a constant speed along a preset track. The potential iscontrolled to perform DC (direct current) electroplating. However, thedeposition rate is not constant so that the micro anode moving in aconstant speed will not lead to constant growing of the deposit. If themicro anode moves too fast, the deposit is gradually reduced in size andfinally grows nothing with increasing the distance between theelectrodes. On the contrary, if the micro anode moves too slowly, thedeposits contact with the micro anode and a short circuit occurs.

The meaning of the constant speed has been lost.

Thus the constant movement of the micro anode is unable to ensure astable deposit rate. Thus the deposit is grown in non-uniform size orthe electroplating may be interrupted. Both have affected the quality ofelectroplated micro components significantly.

SUMMARY OF THE INVENTION

Therefore it is a primary object of the present invention to provide amicro anode guided electroplating device and a method thereof in which aworkpiece is not soaked in an electrolyte (electroplating solution) soas to reduce the contaminations of the workpiece caused by theelectrolyte.

It is another object of the present invention to provide a micro anodeguided electroplating device and a method thereof in which real-timeimage monitoring and capillary action of micro/nanoscale capillary arecombined. A three-dimensional microstructure is deposited on a workpieceat the cathode. The deposit is growing smoothly by the real-time imagemonitoring of the electroplating process.

It is a further object of the present invention to provide a micro anodeguided electroplating device and a method thereof in which an electricfield strength of the micro anode is controlled so that the electricfield strength between the micro anode and the cathode remains stablefor generating deposit with a smooth and uniform surface.

It is a further object of the present invention to provide a micro anodeguided electroplating device and a method thereof in which a monitor isused to monitor the distance between the micro anode and the cathode andcontrol a loading platform carrying the cathode so as to maintain thedistance between the micro anode and the cathode at a fixed value andavoid defects in the deposit.

In order to achieve above object, a continuous micro anode guidedelectroplating device and a method thereof according to the presentinvention consists of a micro anode, a loading platform, a cathode, apower supply and a monitor. The micro anode is formed by amicro/nanoscale capillary filled with an electrolyte and a conductordisposed in the capillary. The loading platform is arranged under themicro anode while the cathode is a workpiece that is put on the loadingplatform to be electroplated. The power supply is connected to theconductor of the micro anode as well as the cathode so as to supply abias to the micro anode and the cathode and generate a deposit on thesurface of the cathode. The monitor is connected to the power supply aswell as the loading platform. The power supply provides the monitorelectricity and the monitor checks the distance between the micro anodeand the cathode so as to control movement of the loading platform andadjust the distance between the micro anode and the cathode into a fixedvalue.

In a continuous micro anode guided electroplating device and a methodthereof of the present invention, the micro anode is firstly set abovethe cathode and an electrolyte is added into the micro anode. Then applya bias to the micro anode and the cathode so that a deposit is generatedat the cathode. Next take an image between the micro anode and thecathode. Finally, check a distance between the micro anode and thecathode according to the image and the loading platform is controlled soas to maintain the distance between the micro anode and the cathode intoa fixed value.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present inventionto achieve the above and other objects can be best understood byreferring to the following detailed description of the preferredembodiments and the accompanying drawings, wherein

FIG. 1 is a schematic drawing showing structure of an embodimentaccording to the present invention; and

FIG. 2 is a flow chart of an embodiment according to the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Refer to FIG. 1, a continuous micro anode guided electroplating device 1includes a micro anode 1, a loading platform 12, a cathode 14, a powersupply 16 and a monitor 18. The micro anode 10 consists of amicro/nanoscale capillary 101 and a conductor 103. The conductor 103 ismade from platinum and is disposed inside the capillary 101 that isfilled with an electrolyte (electroplating solution) 2. The loadingplatform 12 is set under the micro anode 10 and is having a drivingdevice 121 therein. The driving device 121 drives the loading platform12 to move. In this embodiment, the driving device 121 is a motor. Thecathode 14 is a workpiece that is put on the loading platform 12 forelectroplating. The power supply 16 is composed of an anode and acathode. The anode of the power supply 16 is connected to the microanode 10 and the cathode of the power supply 16 is connected to thecathode 14. The power supply 16 supplies a bias to the micro anode 10and the cathode 14 so that a deposit is generated at the cathode 14. Themonitor 18 consists of an image capture device 181 and a controller 183.In this embodiment, the image capture device 181 is a CCD(Charge-coupled Device). The image capture device 181 takes an imagebetween the micro anode 10 and the cathode 14 and sends the image backto the controller 183. Then the controller 183 performs binary imageprocessing so as to check and calculate the distance between the microanode 10 and the cathode 14. The distance between the micro anode 10 andthe cathode 14 must be maintained at a fixed value. Thus the controller183 controls the movement of the loading platform 12 according to thedistance between the micro anode 10 and the cathode 14 calculated bymeans of the image so as to adjust and maintain the distance betweenmicro anode 10 and the cathode 14 at a fixed value. The controller 183is a computer.

Refer to FIG. 2, a flow chart of an embodiment is revealed. As shown infigure, a continuous micro anode guided electroplating is performed bythe device mentioned above. At first, take the step S10, disposed themicro anode 10 above the cathode 14 and the micro anode 10 is slowlyclose to the cathode 14. Then run the step S12, add an electrolyte 2into a micro/nanoscale capillary 101 of the micro anode 10 and theelectrolyte 2 forms a semicircular drop on an opening of the capillary101. When the micro anode 10 is getting close to the cathode 14, thesemicircular drop contacts with the surface of the cathode 14 in asemilunar form (a great C-shaped) due to surface tension.

Next refer to the step S14, apply a bias to the micro anode 10 and thecathode 14. Then take the step S16, metal ions in the electrolyte 2 ofthe micro anode 10 are deposited at the cathode 14 to grow into adeposit on the surface of the cathode 14. While the deposit is growing,run the step S18, take an image between the micro anode 10 and thecathode 14 by the image capture device 181 of the monitor 18 and theimage is sent to the controller 183 of the monitor 18 by the imagecapture device 181. Later take the step S19, estimate a distance betweenthe micro anode 10 and the cathode 14 by the controller 183 according tothe image because the distance between the micro anode 10 and thecathode 14 must be maintained at a fixed value. The fixed distanceranges from 10 mm (micrometer) to 20 mm. Thus the controller 183calculates the distance between the micro anode 10 and the cathode 14according to the image and controls the movement of the loading platform12.

At last, repeat the step S10 to the step S19 mentioned above until thedeposit grows into a preset shape and structure. By the real-time imagemonitoring and capillary action of the micro/nanoscale tube, athree-dimensional microstructure is deposited on the workpiece at thecathode. The deposit is growing smoothly under the real-time imagemonitoring.

In summary, a micro anode guided electroplating device and a methodthereof of the present invention reduce contaminations of the workpiecebecause the workpiece is not immersed in the electrolyte. The microanode guided electroplating device and the method thereof combinesreal-time image monitoring with capillary action of the micro/nanoscaletube. A three-dimensional microstructure is deposited on the workpieceat the cathode. The deposit is growing smoothly under the real-timeimage monitoring. Moreover, an electric field strength of the microanode of the present invention is controlled so that an electric fieldstrength between the micro anode and the cathode remains stable. Thusthe deposit is with a smooth and uniform surface. Furthermore, by amonitor, the distance between the micro anode and the cathode ismonitored and the loading platform carrying the cathode is controlled soas to maintain the distance between the micro anode and the cathode at afixed value and prevent defects in the deposit.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details, and representative devices shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A method of continuous micro anode guided electroplating comprisingthe steps of: disposing a micro anode above a cathode, adding anelectrolyte into the micro anode, applying a bias to the micro anode andthe cathode, generating a deposit at the cathode from the micro anode,capturing an image between the micro anode and the cathode, and checkinga distance between the micro anode and the cathode according to theimage and controlling movement of a loading platform so as to maintainthe distance between the micro anode and the cathode at a fixed value.2. The device as claimed in claim 1, wherein the fixed value of thedistance ranges from 10 mm (micrometer) to 20 mm.
 3. The device asclaimed in claim 1, wherein the image is treated by binary processing.4. The device as claimed in claim 1, wherein the micro anode includes acapillary and a conductor while the conductor is disposed inside thecapillary.
 5. The device as claimed in claim 4, wherein the conductor ismade from platinum.